I shipped my T5 a few years back, from Indiana to Florida. I believe I went UPS, and it was under 100$. Is it an AOD or T5? For some reason I remember my T5 being right under the weight cut-off limit, so an AOD is probably going to be more expensive than what I payed.
The MOST important thing is making sure you pack it very well. Make a cradle for it from 2x4s that will slide into the box. No cardboard box will hold a trans by itself.